In many applications, the safe coupling of connectors is of high importance. For example, in the case of car safety systems, as e.g. airbag systems in passenger cars, the connectors used for the connection of an airbag to its ignition base have to be provided with reliable safety systems. To ensure that the connectors cannot become loose unintentionally, secondary locking means are used in addition to the primary locking means to guarantee a safe mechanical coupling.
An example of a connector with a secondary locking means is described in WO 97/41623 A1. This document discloses a connector which can be mated with a corresponding counter-connector being part of an airbag ignition mechanism. In assembled condition, (i.e. the connector is mated with the corresponding counter-connector), the connector is fixed to the counter-connector by means of flexible latching arms. During mating of the connectors, these arms are deflected and snap back into corresponding latching clearances of the counter-connector, when fully mated. For securing the mechanical coupling of the connectors, WO'623 suggests a secondary locking means that comprises locking arms that can be inserted into the mated connector assembly. Once the locking arms are inserted, they inhibit bending of the latching arms out of the corresponding latching clearances. Thus, the mechanical coupling of the connectors is secured.
A further development of a secondary locking means is disclosed in the patent application DE 100 05 858 A1. This document discloses a connector with a secondary locking device and a safety spring element, which serves to hold the secondary locking means in a position, in which the secondary locking means is mounted to the connector housing so that it does not hinder mating or un-mating of the connector with a corresponding counter-connector.
In patent application WO 2014/072081 A1, a connector assembly is disclosed that comprises a secondary locking means and a spring. The secondary locking means and the spring are assigned to a connector housing. Hereby the secondary locking means is movable between a first and a second position. When placed in its second position, it serves to secure the mating of the connector housing to a corresponding counter-connector. During mating, the spring is biased to cause the secondary lock to move automatically into a locked position when the connector assembly is fully mated with is corresponding counter-connector, without need for an operator to push the secondary locking means into the locked position.
The connector assemblies described above have in common that a partial mating of the connector and the corresponding counter-connector is possible, in which case the secondary locking means do not function satisfactorily.
If the connector is only partially mated, it might occur that the connector assembly electrically functions correctly, since the electrical contacts of the connector and the corresponding counter-connector are connected (i.e. current conduction is possible), but the mechanical connection is not according to the desired specification. In a highly safety relevant connector assembly, for example in airbag restraint systems, often detecting devices are integrated that are able to detect a correct mating of the counter-connectors based on electrical circuits that are opened respectively closed during the mating of the connector. If the connector and the corresponding counter-connector are partially mated, these detecting devices may report untruly a correct mating of the connectors. Further, with the prior art secondary locking means it was often possible to move the same in the locked position, thereby indicating to an operator, that the mating is complete. However, in case of only a partial mating, the prior art secondary locking means often fail to provide the desired secondary locking function. In the case of e.g. airbag restraint systems the electrically functional but mechanical disturbed connector might disengage due to vehicle vibration.